System for preventing electrolysis.



W. B. POTTER.

SYSTEM FOR PREVENTING ELECTROLYSIS. I APPLICATION FILED FEB. 20. l9l5- '1 1 9 1 ,6 1 1 Patented July 18, 1916.

I II l4 at I Fig.2. Fig.5

Volts Volts Miles Miles Wi nesses: Inventor": Me William s ot er:

N TED 's'r 'rEs PATENT OFFICE- WIL IAMB. ro'rrnn,

OF SCHENEGTADY, NEW YORK, ASSIGNOR T O GENERRL E LECTBIC COMPANY, LA CORPORATION OF NEW YORK.

sxsi'nm FOR PREVENTING nnnccrnoifirs s.

Porrnn, a

"lowing is a specification.

M invention relates to. a system for preventlng electrolysis, and more particularly to the application of such a system to elec- I tric railways.

' Where the rails of an electric railway are used as return conductors, it is frequently found that stray burrents escape from the rail to ground and thence to earthed metallic structures, such 'as water or gas pipes.

These escaping currents will enter the pipes at points remote from the powerhouse, where the rails are-positive to the pipes, and travel therein until, at points near the power-house, the pipes become positive to the rails. Current will then-leave the pipes and pass back into the rail. Wherever ourrent leaves the pipes, an electrolytic corrosion is caused, which often seriously damages the 'ipes. T

It has een previously proposed, in those systems where both positive and negative insulated feeders are employed, to insert a series booster m the negative feeder and to excite thebooster field with a current proportional to that flowing in the corresponding positive feeder. As will be evident, how,-

ever, the successful operation of such an 'arrangement presupposes that the current'returning from any one. point corresponds ence between the rai with the current sent 'out' over "the related positive feeder,-whereas in ,a complex systemitis unlikely that such a relation will exist.

The object of my invention,then, is'to devise a' system whereby s and, adjacent pi will be minimized and --th is'-relation maintained'throughout all conditions of operation.

. In theappended claims 1" have" definitely pointed out the novel features characteristic {of my invention.

'- The details of corral Eruption arrangement and the mode of operation of my system are more fully describedin the following specification when takenn'n connection with the accol npanying drawing, in which the potential differ.

Patented Ju'1 1s, 1916.

Application filerll'ebruary 20, 1915. Serial No. 9,547.

. Figure 1 is a diagrammatic view illustratmg my system applied to an electric railway. Fig. 2 1s a diagram showing the rela-- tive potential of the various conductors throughout the length of the. line before the appllcation of my system while Fig. 3 is a similar diagram showing the conditions obtained after its use.

. In the simplified case herein illustrated, power is supplied from the generator 10 through the trolley 11 to the electric car- 1'2, and returns to the generator through the rails 13, only one of which is shown. Adj acent the rails is a pipe system 14, which may represent a gas or water main, extending more or less parallel to the tracks from a point remote to the generator to a point near the generator. Connected to the negative terminal of the generator and to a point near the end of the track is a feeder 15 preferably insulated from ground, and in series with this feeder is the armature of a booster 20. Although I have shown the booster located near the end of the track this location 7 l is not essential. This machine is driven in any "desired manner, and it is here shown as mounted on the. same shaft with a motor 21 supplied with current from the trolley. The

\field 22 of the booster is separately. excited by means "of an exciter 23, here shown as direct connected to the booster set. In se ries with the field winding 24 of the exciter is a resistance 25. A regulator is then supplied to control the field of the exciter inaccordance. with the potential difference between'the track and the pipes. This regula- .tor comprises a coil 30 connected between said points and responsive to variationsof currents therein. A spring held pivoted ar-v mature 33 is arranged, when attracted by the flux produced by the co1ls 30 and 31, to

.short circuit theresistance 25 in series with the exciter field. i

I Conditions before the application of my system havebeen illustrated in Fig. 2,-

whereas the' conditions obtained by the use of my system are shown in Fig.3. The ordinates represent voltages, considering the negative terminal of the generator is zero,

- the potential difference. In addition a coil while the abscissae represent distances away 2, the potentialgradient R of the rails starts 65 forced through the negative feeder, being taken out of the rails and forced into the di eren'ce between the rails and the p1p has been reduced, the armature 33 Wlll be released and the resistance 25 reinserted in at the negative terminal of the generator and the exciter field circuit. This action will be 70 gradually increases to the outer end of the rapidly repeated with the regulating efi'ect l1ne. Similarly, the gradient P of the pipe common to regulators of this type. system gradually rises, but it will be noted It willbe understood that while for the l that at points near'the end of the line,-the sake of this application I have shown the 5 ra1 ls are posltive to the pipes, whereas at simplest form of electric railway system, it

po nts near the generator the pipes are posiwill, nevertheless, hold that, however comtive to the rails. It, therefore, follows that plex the system, the use of the apparatus there is a flow ofcurrent into the pipes at which I have described will result in maintheir outer ends and out.of the pipes at taining an approximately zero difference of 80 points near the generator. Electrolytlc cor- 'pOtGHtlfll between the rails and pipes at ros1on W1ll accordingly result at the latremote points, and in forcing current P through the negative feeder. I have there- Itjwlll readily be seen that if I can refore accomplished the' desired result. It d uce the potential difference between vawill of course be understood by those sln'lled nous points in the rails, that there will be a in the art that, although I have herein illusles s tendency for stray currents-to leave the trated and described myv invention as apralls to pass through the ground and pi es. plied to an electric railway using direct cur- V have, accordingly, supplied; a so-ca ed rent for the prevention of electrolysis, the negative feeder, connected to the negative principle thereof is equally applicable to a terminal of the generator and by the insystem using alternating current for the troduction of an electromotive force at purpose of neutralizing inductive disturbv some pomt therein, as for instance at its ances in neighboring telephone or telegraph outer end, I so raisethe potential at this conductors.

- 30 point, as shown by F in Flg'. 3, that a con- Although I have herein shown and desiderable port-Ion of the current returned to scribed one preferred form "of ap aratus the power-house is forced through this which may be used to carry into e ect my feeder. If properly regulated, the result invention, I wish it understood that similar mg potentla gradient of the rails will asresults can be obtained by the use of equiva- 35 sume a form such as that shown at R in lent apparatus, and I, therefore, seek to Fig. 3, from which it will be seen that the cover in the appended claims all those modipomt'of highest potential in the rails is now fications and equivalents which are within ntermedlate the generator and the extreme the scope'and spirit of my invention. end, and at the same time, is markedly re- What I claim as new and desire to secure 40 duced from its potential without the use of by Letters Patent of the United States, is

my system. Furthermore, the potential dif- 1. In combination an electric railway sysference between the rails and the pipes,- tem comprising a plurality of return conwhose potential gradient may now be conductors, one of which is in contact with the sidered as coinciding with the base line at ound and another of which is insulated 45 the extreme end of the line is minimized, om the ground,,an adjacent earthed me.- and may, by adjustment of the battery 32, tallic structure, a source of E. M. F. in series be brought tozero or, reversed. If brought with said insulated conductor, and means t zero, a current flow from intermediate for. controlling said source responsive to the points of the rails toward both the generotential difl'erence between the conductor 5 ator and the outer end, would result, If, in contact with the ground and said earthed now, the load conditions are such that the structure. electromotive force introduced by the 2. In combination an electric railway sysbooste'r is insuificient to force the desired tem comprisin a plurality of return conamount of current through the negative ductors, one 0 whiclfis in contact with the '55 feeder so that the potential difference beground and another of which is insulated 12o tween the rails and pipes is not reduced to from they ground, an adjacent earthed mezero, then the solenoid 30 of the re ator tallic structure, a source of E M. F. in v -W1ll be ener zed, and'if the potential difseries with said insulated conductor, and

O ference is'su ciently great, the armature 33 means for controlling said source compris 60 w1l l be attracted,- thus short circuiting the ing a coil responsive to the potential dif- .reslstance 25 and increasing the current in ference' between the conductor in contact the field-winding 22 of the booster. The with the ground and said earthed structure booster potential will thereby be-increased, and a separately excited coil. and a larger amount of current will be 3. In combination an electric railway system comprising a plurality of return conductors, one of which is in contact with the ground and another of which is insulated from the ground, an adjacent earthed me-" tive feeder connected between the negative terminal of said generator and a remote point in said rail and insulated from 20 ground at all intermediate points, a booster in series with said feeder to aid the flow of current therein, and means for regulating the voltage of said booster in response to the potential difference between said rail near 25 its connection to said feeder and said earthed structure.

In witness whereof, I have hereunto set my hand this 17th day of February, 1915..

WILLIAM B. POTTER."

Witnesses:

EDITH L. GERMOND, BENJAMIN B. HULL. 

